


Day 11: Sadism/Masochism & Gags

by Ked_from_safe-skeletons (Sinnychild)



Series: Kinktober 2017 [2]
Category: Undertale (Video Game)
Genre: Consensual, Crying, Daddy Kink, Dirty Talk, Dom/sub, Gags, M/M, Obedience, Overstimulation, Praise Kink, Restraints, Spanking
Language: English
Status: Completed
Published: 2017-10-26
Updated: 2017-10-26
Packaged: 2019-01-23 15:40:46
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,381
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/12510652
Author URL: https://archiveofourown.org/users/Sinnychild/pseuds/Ked_from_safe-skeletons
Summary: Sans always disobeys. Gaster will make this stop.





	Day 11: Sadism/Masochism & Gags

**Author's Note:**

> You can find me on the tumblr [@sinful-skeletons](http://sinful-skeletons.tumblr.com) that I share with a fellow writer! Twice the stories, twice the fun!
> 
> [Here](https://sinful-skeletons.tumblr.com/post/166308005701/day-3-public-biting) is the line-up for Kinktober :)

Sans was winking at Gaster, who looked at him with a painful expression on his face. His son was at his mercy, laid on the bed, his hands restrained above his skull, and he still had the need to be a damn smart mouth.

“Sometimes, it feels like you wish to be punished, my son.”

“maybe i am.” Sans answered playfully.

_ “That’s enough.” _

Gaster’s voice had snapped and Sans jumped. His father usually didn't answer so harshly when he disobeyed. Sans had been instructed several times since the beginning of the scene to stay quiet but the scientist loved to punish him - just as Sans loved being punished, the very reason of his continued disobedience. This time though, Gaster sounded deadly serious and his son shut his mouth, caught by surprise. The tall skeleton usually liked having occasions to fulfil their desire for inflicting (or receiving) pain. Why was he so upset right now?

“I am tired of this, my son. I wish you would trust me to give you what you need, but it seems like you're convinced that you need to push me so I satisfy you enough. Patience needs to be taught to you. If you could just wait, as I ask of you every time and as you never do, you'd understand that you have no need to be punished to get off.”

“but-”

“If you say one word again without my permission, your punishment will be _ literally nothing.” _

Shit. Sans closed his mouth once again and for good this time. This was absolutely not the kind of consequences he had in mind and Gaster was obviously tired of playing along with his games. A punishment was not supposed to be enjoyed after all. It was supposed to remind him of the rules, of the reason said rules had been set up and why he shouldn't have broken them. Sans had more or less forgotten that, always jumping to the fun part directly, provoking with his smart mouth, getting off on punishment and finally forgetting that he didn't  _ need _ to be punished before.

_ ‘Oh damn’, _ Sans thought while the realization was sinking in his mind. He must have really be annoying during the last scenes. How did he end up thinking that he  _ had _ to disobey in order to obtain what he needed?

The silence kept going and it was becoming awfully hard to stay quiet under the staring gaze of his father. He didn't want to protest anymore, but he wanted to apologize now. Gaster was scrutinizing him, analyzing every change of expression, glad to see that his son understood what the scientist meant - but that didn't mean Sans wouldn't learn patience tonight. Two full minutes went like this, Gaster observing Sans and Sans painfully supporting his father’s gaze, forming his tongue in order to bite it and restrain his irresistible need to talk.

“Very good, my son. Is there something you would like to say?”

“i’m sorry, father.”

“That is well. I'm sorry too.”

Sans opened his mouth but closed it just before talking again. He looked at Gaster in disbelief.

“See? If I had trained you properly, you wouldn’t even have thought about asking me why. If I'd trained you properly, you would know you don't have to disobey me to enjoy our scenes. I myself love you so much when you're playing your little rebellion that I forgot some of my own rules.”

Sans shivered upon hearing the unexpected praise. Gaster always showed him his love, both fatherly and romantic, through a myriad of little gestures, but he rarely ever said it. He wanted to speak again, he wanted to be bad, just a little more, only for Gaster to keep being fond of him, but somehow he felt that this wasn't the moment anymore. What his father was doing right now was important for their relationship to keep evolving - he didn't really know why or even how he had guessed that but he was sure of it.

“You failed me, Sans, but it's not your fault. You made a mistake because I failed you first. We will fix this together tonight, do you agree?”

“yes, father.” Sans whispered.

Lust, anticipation and maybe a tiny bit of fear were in his voice. Gaster smiled and leaned down, giving him a skeleton kiss.

“Aren't you a good boy for your daddy! That's okay, Sans. I'm proud of you and I know you'll succeed in what I'll ask of you tonight. Now, I want you to create an ecto-body from your lower ribs to your knees. You will have to keep it until the end.”

This was not too difficult. Focus and a certain level of control over one’s magic were necessary, but Sans had done this too many times for it to be a challenge. His body soon casted blue shadows upon Gaster’s face. His father was still smiling.

“Very well. We will add a new toy tonight. It will help you to stay obedient.”

Sans raised a curious brow and watched the tall skeleton as he was opening a drawer and picking something inside. When he turned his steps back, his son saw how it could be helpful: the toy was a ball gag. They never used one of those yet, which was quite surprising given Sans’ tendency to annoy his peers by talking. And actually, Sans became conscious as Gaster was closing the gap separating them that he didn't like the idea of being muted,  _ at all. _

He didn't mind being restrained, blindfolded, he didn't mind being stuck against a wall, his feet not touching the ground and his soul turned blue, but his words were his last defense line when he was physically completely helpless. It was his weapon as much as his magic and being deprived of it suddenly appeared as unbearable, now that it was imminent. He shuddered and Gaster stopped.

“Why are you afraid?” He asked, watching carefully Sans’ face.

“i-i’m not so sure about that. it's all i have left, why would you want to take it away from me? i swear i'll be quiet, dad, i promise i'll be good, we don't need this!”

“Shhhh, shhhh.”

Gaster cupped Sans’ cheek in his hand and the small skeleton relaxed in his touch, bony eyelids half-closed. His father loved him. He wouldn't do anything that would utterly displease him.

“I will free your right hand so you can have a way to communicate with me. I trust you to not use it and keep it as if it was still cuffed. Your hand is your safeword now. Touching me equals yellow, hitting me equals red. Do you understand?”

“yes, father.”

“Repeat.”

“i have to act as if my right hand were cuffed, but if i need a safeword, i can use it. touching you equals yellow, hitting you equals red.”

“Very good.” Gaster answered while freeing Sans’ hand. “Do you have any questions?”

“what about green?”

“No green. The point of this is that you know you can trust me to please you. Something else?”

“nope…”

“Can I gag you now?”

Sans shuddered again and he looked down at the ball, his pupils vanishing and reappearing after a split second.

“green.” He murmured for the last time tonight.

“You're such a good son, Sans. I will make you feel very good, I promise.”

Gaster had always taught Sans to never promise anything unless he was absolutely sure to respect it. The two skeletons were very wary of that word and Sans knew his father didn't say it lightly. He slightly relaxed and nodded. Gaster reached the back of his skull and secured the ball gag before taking a step back and admiring the picture.

“You're so beautiful, my son. I must admit that the sight of you helpless and not even able to protest is very arousing.”

Sans emitted a moan through the gag. Gaster reached out a hand to his son’s already slick entrance and started to stroke him. Soon, his fingers were blue from Sans’ magic and he slipped two of them in the offered pussy. He went at a slow, steady pace, and it wasn't long before the short skeleton started to wiggle, trying to bury his father’s fingers deeper.

“Shhhh, Sans, everything is okay. Your daddy got you, he will take good care of you. Be good and you will feel good.”

Sans whined but stopped fidgeting. He was already feeling good for sure, but the rhythm was desperately  _ slow, _ and there was no way he could get off of that. That was just the beginning for sure, but with all the teasing and raised expectations, it already felt like torture. He wanted more and Gaster hadn't even touched his clit yet, focused on his vagina.

His father slowly removed his fingers and licked them thoroughly, cleaning Sans’ juices off them. Sans wanted to close his eye sockets to at least limit the sources of pleasure, but he knew Gaster would never let him go with it. He focused on the sight instead of ignoring it, trying to think only of this and not of his throbbing clit, desperate for attention.

“Such a good boy for his daddy...” The scientist murmured. “You're so tempting, my son, I don't think I'll wait much longer.”

He stroked his half-hard cock under the hazy gaze of Sans, who was whimpering helplessly again the ball gag. It only took a few passages of his hand before his dick was fully erect and he leaned down on Sans, lining them up. His tip stroked the folds of his son’s puss, drawing more whines from him. The short skeleton was obviously doing an honourable effort to obey and avoid wiggling and Gaster smirked. He entered in the wet magic at such a low pace that even him had to focus hard to avoid smashing himself in.

_ ‘please daddy your cock feels so good in me fill me up i swear to the stars i need you so much fuck me fuck me fuck me pleeaase’ _

Only incoherent grumbles passed through the ball. Gaster stayed absolutely still once he buried himself deep into Sans. He never saw his son so frustrated and was loving every bit of it. He kissed Sans on his forehead, on his cheeks, everywhere he could access, tenderly, lovingly, softly. And finally, he started to move his hips, attracting more and more moans from Sans. Still tho,  _ it was so damn fucking slow. _

Honestly, if one would forget about the gag and the restraints, it was the most vanilla sex they had in a while. 

“That's it, Sans, take all of daddy’s cock. I can feel your walls tightening around my dick… You're so eager, son! Don't worry, daddy will give you all of what you need.”

It was  _ so desperately good, so desperately frustrating.  _ Soon enough, muffled moans and whimpers were filling the room, while Gaster kept his pace down. Sans didn't even know anymore if it was pleasant and painful. It seemed like it was like this since the eternity when his father talked again, making him violently jump out of his mind lost in frustration.

“If I remove the gag, will you be good, son? Will you stay quiet?”

Sans nodded in frenzy, so much he almost hurt his neck. He would have shut up for the next month if it was what it took to just  _ be able to cum.  _ Gaster reached out ghost hands to the back of Sans’ skull and removed the ball gag in one smooth move. The small skeleton breathed heavily. He was going to die if he wasn't fucked thoroughly  _ right now. _

And Gaster kept moving slowly. Sans wanted to smash his free hand on his hips to force him to go harder, but he couldn't even do that; because of their ‘safeword’, his father would have stop entirely. He gritted his teeth in despair, having more and more trouble not begging Gaster.

“You seem to have something to say to me.”

“nggggggh.” Sans growled.

“I'm very proud of you, son. You're doing so good.”

It was almost a meow this time escaping Sans’ teeth, in a high-pitched voice that made him blush. Gaster smiled. His son had deserved his reward.

“You can talk.”

“ _ oh stars please father i’m begging you fuck me fuck me hard until I can't stand make me cum with your big cock please please pleeeeaaaas-! _ ”

He got interrupted by Gaster suddenly standing on his knees with Sans’ legs on his shoulders. His ecto-butt was up in the air that way and the new angle made him gasp. A bulge was visible on his tummy, the purple cock of his father shining under the blue flesh.

“You still haven't got your punishment for your earlier behaviour.” He rumbled in Wing Dings, forgetting in his excitement to use a common font.

It didn't stop Sans for understanding him, though, and he shuddered with expectation a split second before everything crashed on him.

Gaster’s ghost hands started spanking him hard while the talk skeleton suddenly thrusted in him without a word of warning.  A third ghost hand was on his clit, neglected since the beginning. The intense pain mixed with pleasure made Sans cum almost immediately. Gaster rode him through his orgasm, without stopping the spanking, until his son was crying from the pain and overstimulation, lost in a bliss he never got to experience before. The tall skeleton wasn't long to come after that, his cock imprisoned in the clenching inner walls almost painfully.

As soon as he got down from his orgasm, he slipped out of a whimpering Sans and laid him down on his stomach. The purple seed was swaying beautifully in the blue magic, but he didn't lose time to admire this, watching a lower zone to check the result of his work. There was purple here too, but it was only Sans’ magic bruising from his spanking. He started to stroke him with smoothing hands, drawing a sigh of relief from Sans - who didn't look like he was going to talk again soon.

“I know what you need to get off, son. You don't need to be punished. You just need to be patient.”

“... iloveyou.” Sans mumbled.

“I love you too.”

**Author's Note:**

> I really hope you liked this one, this is my favourite so far, it is clearly above the first two I already wrote. Please don't hesitate to criticize!


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